Electric machine



Nov. 10, 1942. H LlsT 2,301,425

ELECTRIC MACHINE Filed March 29, 1939 4 Sheets-Sheet 1 i Aff n Nov. 1o,194,2. Q UST v2,301,425

ELECTRIC MACHINE Filed March 29, 1939 4 Sheets-Sheet 2 Mya/7 or:

Nov. 10, 1942. H, UST 2,301,425

vELECTRIC MACHINE Filed March 29, 1939 4 Sheets-Sheet 3 Nov. 10, 1942.H. Lis-r 2,301,425

ELECTRIC MACHINE Patented Nov. 10, 1942 UNITED 'STATES Plrr'lzm OFFICEELECTRIC MACHINE Application March 29, 1939, Serial No. 284,703

In Germany March 3l. 1938 lClaims.

The invention relates to an electric machine which ilnds principalapplication as a small electric motor. The machine can however ybe usedas a current generator. The purpose oi' the present invention is,broadly, to provide a small direct-current-operated electric machinewhich has improved eillciency.

Various endeavours have been made to simplify appreciably the existingelectric motor i n order to create thereby a so-called small electricmotor. Such smallfelectric motors have however an extremely pooreillciency. So long as they are supplied from the mains or from largebatteries the eillciency is oi' no signiilcance when the relativelysmall consumpt o! such motors is consideredt However, as soon as only adry battery is available for the operation of these motors andcontinuous operation is desired the heretofore known small motors fallshort on account o! their much too high current consumpt.

The purpose of the invention, namely to provide a small electric machinewith improved eiliciency, is attained by virtue ot the fact that therotor is a permanent magnet and the stator has winding-excited poles.and the excitation of the poles takes place successively in a givenordei by lmeans of an improved control of the exciting current for thestator poles. This construction allows a permanent magnet armature to beincorporated in the rotor.

According to the invention the control of the exciting current for thestator poles may conveniently be eilected either directly orindirectlythrough the intermediary of the rotation of the rotor by meansof a mechanical operative connec-'sion between a current controller andthe rotor. Such current controller includes switching devicesconstituted each by lnter-contactible elements provided at fixedlocations in accordance with the number and location of the stator polesand connected electrically inclrcuit with windings for the respectivepoles. The switching devices are actuated successively by rotation ofthe rotor by virtue o! cam or eccentric means included in said operativeconnection. In the case oi an eccentric it acts on the switching devicesin such a way that one switching device commences to open only when thesucceeding switching de- A vice is already closed, that is to saytherefore, in such a way that the closed-contact periods which followone another overlap. This arrangement has the particular advantage thatthe spark iormation is small and a continuous and impulse free, rotationof the rotor is obtained.

AThe control o! the exciting current may be 55 effected simply by oi therotor shaft.l On this part there'rests a ball-bearing whose inner ringis free to rotate relative to the outer ring. n rotation o! the 5' shaftthe ball-bearing'psrtakes ot-a'n eccentric motion and.' as a. movableone oithe intercontactible elements in each switching device restsagainstthe' outer ring ot the ball-bearing.

. movement o! said elements from contactingto non-contacting positionsand hence control of the exciting current is possible.=5aid elementsare` conveniently constituted by resilient tongues, not only said oneelement but both elements being in such case movable. Obviouslythemovement of the elements can take place indirectly from theeccentric. Resilient or other tongues might even bear directly on theeccentric part oi' the shalt provided that insulating additions on theends o! the tongues bear on theshaftri Y 'I'he stator irons'are normallylaminated in the usual way. In one embodimentof the" invention thestator irons are T-shaped anddisposed with their length parallel to theaxis off-the rotor. The tree ends oi the stator` irons,l ine; the endswithout heads. are supported inv a packet which forms at lthesaxne timean iron ilux-return-path. This sheet metal 'packet supports the statorirons withinthe.prei'erably cylindrical. housing of the mach-ine.` Theenlarged heads which formthe poles'fare'fsupported in a transverse wallin the housing, insulating material. These poles arepresented axially tothe armature of .therotsrI thearmaturs being located on the sideofzthe'insulating wail opposite trom the stator irons, a i'irst bearingfor the rotor shaft being provided insaid insulating wall and theswitching devices are located between the rotor and a second bearing forthe rotor shaft provided in theiaceplate o! 'the hous- 40 ing. Thisconstruction of the 'machine makes possible very small. dimensions inspitsfot which the individual parts are-easily inspected and can beeasily adjusted. An appreciable advantage ot this machine is moreoverthe high eillciency as compared with known constructions.

The rotors amature may be constituted as a permanent magnet with two ormoreiipoles and it is also possible to employ what may beregarded as asingle-pole armature. In-'this case the magnetic part of the armatureconsists of a sector shaped plate mounted on the shaft and overlappingat least two successive stator'poles. The single operative pole oi' thisplate lliesopposite the stator poles. As the sector shapedmagnetoccupies only a portion o! s circular oilsetting a part thofwall beingot by three partitioning walls 3, I and l, and an insulating plate l issupported on the inner surface of the cover 2. In the plate l and thewall l, which likewise consists of insulating material, thehall-bearings for a shaft 1 are provided. An armature l (Figs. 1 and 2A)is nxed to the shait 1 and these parts together constitute the rotor.The armature carries no windings but consists of steel with a highcoercive force and magnetknown in themselves are employed in order toised to constitute a permanent magnet with, in

reduce friction. Por example it is preferable toJournaltheshaftottherotorinconiealbearings and to balance the rotatingparts satisfactorily. Ifaiargernumberofpolesisemployedinthe abovedescribed electric machine then the eurrent controllerforthestatorpolesmay consist of two nxed contact rings which arearranged concentrically with one another and betweenwhichacertainclearanceisleit.Intothisclearanceproiecttheendsofcontacttongueswhicharearrangedinaccordancewiththenumberand position of the stator poles.These contact tcnguesarecontrolledbyacommoneecentricorthelikeandbearalternatelyontheouterorthe inner contact ring. Thisarrangement has. moreover. the especial advantage that completeinterruption oi the current does not occur. On the contrary the currentflows continuously through the exciting windings of the stator.

The improved emciency oi' the electric machine described above isprincipally a consequence of the mode ci construction ofthe stator.Itispoesibie-without dimcultytooheerve the most favourable relationshipbetween the length of a coilanditawindingheight. Inthiswaythere followsthe most favourable use of the copper winding andthe greater part of theiron circuit is enclosed. There are no considerablesupernuousironbodies;onthscontrary,intheconstructionvisualisedaboveonlysomuchironis usedasisnecessary.Theelsctricandmagnetic lossesaretherefore reducedtoaminimum..

ts oi the invention are illustrated,bywayofbeingexampleeoftheinventiomin theacccmpanymgdrawinas:

Pig.1showingalongitudinslsectlonthrough t. acromsectiononthelineI-IofandFlgJAisanendviewoftherotor seeninthedirectionowolitetol'ig.2.

acrossaectiononthelineII-II l'lg.8isawiringdisgramoitheexcitatloncir ofany ci the modincations according to In rigore. 1 u s numeral 'ldesignates a cyundrieal housing which is closed by a removableThllnterlnrofthehoilinlisdivided this particular case, two poles. 'I'hepartitioning wall I is formed oi laminated iron and constitutes a baseplate for the stator and an iron flux-return-path. In this wall thereare secured in this embodiment three stator irons I. constituting polebodies, which uniformly spaced around the periphery of the housing aredisposed parallel to the shaft 1. The stator irons are enlarged towardsthe ends directed to the rotor so that poles Il are formed presented tothe amature. Most simply the poles are produced by giving the statorirons a T-shape and supporting the T-heads in the partitioning wall I.The stator irons are. like the wall l, laminated. On each stator iron isprovided an exciting winding Il.

The current-controller for the' exciting current for the winding iiderives support from projections i2 o'iythe plate l. Each switchingdevice in the current controller consists of two resilient tongues I3having contact pieces i4 and constituting inter-contacting elements. Thetongues il are so adjusted that in their undisturbed setting thecontacts i4 do not touch. The number and position of the devices il, I4conform with the stator poles il. Each switching device is connected, asFig. l shows. with the corresponding excitingwinding il and with thesource of current in such a way that when contacts Il touch directcurrent from the terminals of the machine flows through thecorresponding winding ii andaparticnlarpoiarityisimpressedontbecorrespending pole il.

The actuation oi the devices i8, il in this ease is effected insuccession by a ball-bearing il which is provided on an eccentricportion il oftheshait 1. Theinnerrlngoftheball-bearing is free to rotaterelatively to the outer ring I1 and therefore the outer ring on rotationof the shaft 1 partakes. together with the eccentric part, oi a swingingmovement, and as one tongue oi' each set of tongues Il,` il bearsagainst the outer ring i1 it is thus that the switching devices are oneafter the othercloeed and then opmed. Correspondingly the stator polesare successively excited and the exciting current then switched ofi'. Inthis way a kind of rotating neld is produced in the region of thearmature by means of a direct current'snd by the interaction of thesuccessively excited stator poles Il and the poles of the permanentmagnet t the rotor is maintained in rotation.

The eccentric means for actuating the currentcontroller may be regardedas a part rotatable with the rotor and having a zone ot increased radiuswhose angular extent, limited by the minimum' radius which will closethe tongues of the switching devices. is at least equal to the angulrdistance between two successive switching deees.

In the embodiment according to Figs. 4 and 4A a permanent magnet Il isarranged in the middle of the stator base plate l which magnet gives tothe poles of the stator irons a given polarity winch is periodicallystrengthened or weakened by means o! the exciting current. A "singlepole armature la is employed which is sector shaped and preferablyoverlaps two stator. poles. The remaining circular area is iilled by asector il ot non-magnetic material. 'l'he mode oi' opera- 'tion is thesameas in the embodiment described above.

WhereasFlgures itoishowanelectric machine in which the stator andarmature iie one behind the other in the direction oi the shalt linl*igures.' to'ithereistobeseeria'machine in which the armature isdisposedwithinthe cor .statorasinthe conventional motors. The

ing consists of two parts Il held together by screw bolts 2l. Theconcentric arrangement oi the rotor and stator necessitates a specialcoil shapeasshowninl'iguresiiandbymeansoi which a further increase oithe etliciency oi the machine is attained.

'l'he current-controller according to Pigs. 0 and l0 consists of twoilxed concentric rings il and il between which are arranged rilienttongues u in accordance with the number and position oi' the poles andwhich are actuated by an eccentric :I in order to supply current to thewindings o! the stator poles. In Pig. 9 the wiring from the supplyl tothe current controller and thence to onlyasinglecoilliisgivemailoithecoilsbev ing however electrically connectedidentically to one another except as regards angular relationship. Thisrelationship will be clear yfrom Pig. l0, which shows the connectionsfrom all the Pairs ci tongues 2l (conventionally represented) to the 3orespective coils Il. In these Figs. 9 and l0. parts associatedwiththepartsitoll havebeengiven the same reference numbers ascorresponding partsinl'igalto. Thisal'rangementworks asacurrentreversersothatallthepoles'are40- almost Acontinuously excited. 'I'heeillcieney o! themachineistherebyincreasedandonaload basis the weightand the dimensions are reduced. Referring to-Fig. l1. in theconstructionthereinshowntwosetsofcoilsiiandilaarearrangedonthestatorironl.ThecoilsetIIis, asdescribed with reference toPigure l,connectedtbthesourceofdirectcurrentandiothecurrent-controller itmorder-.to impressperiodically a given polarity on the polea I.. Byvirtue ot 5o thiscontinuingchangeinthepolarityofthe stator poles and therotating magnet-armature v l an alternating or reversing current isgenerat ed in the coils lia. The ,current generated in thecoilsiiaisledtotheterminalsbywayofoo a current-distributor including tonguesIlo and generally similar to ythe current-controller Il. The arrangementis such that the current is sent from the machine in one direction bymeans ci' this distributor as by means o! a commutator. so

Theshaitlhasasecondeccentrlepartilaon which a ball-bearing iIo undergoesa swinging movement and thereby moving the tongu` Ita I actuates thecurrent distributor.

By means o! a motordrlven generator such 'as 65 showninlrlgureilitispossibleiorexampleto drive by a 4 voit battery and take from theter' minalsoithe generatorpartadirectcurrent potential oi' 100 voltsand, for example. use it forananodecurrentcircult.' l

Iclaim:

l. An electric machine comprising a stationary, structure, acontinuously rotatable structure incorporating a permanent magnetamature, a

plurality of pole bodies incorporated in the sta- 75tionarystructureandpresentingtosaidarmature a plurality oi poles atangularly spaced positions with reference to tbe axis oi rotation of therotatable structure; windings applied to said polebodieatherebeingawindingioreachpolebody, a current-controller connectedelectrically in circuitwithsaidwindingaaneccentriconthe rotatablestructure` and a ring Journalled on the eccentric to actuate saidcurrent controller under the control ci' said eccentric. thecurrent-controller being adapted on actuation to allow current to besupplied to saidwindings successively to impress alike polarity on saidpoles successively. 2.` An electric machine comprising a stationarystructure.. a continuously rotatable structure incorporating a permanentmagnet armature. a plunuty or pole bodies incorporated in the ststionarystructure and presenting to said armature a plurality of polesatangularly spaced positions with reference to the axis oi' rotation oithe rotatable structure, windL'igs applied to said pole bodies therebeing a winding for each pole body, means for supplying direct currentto said windings. a current-controller consisting of sets ofintercontactible elements there being a set oi' such elements connectedelectrically in circuit with the winding for each pole body, a freelyrotatable ring against which bears a movable oneo! said elements ineachv set, a circular mounting for said ring. tbe mounting being earriedby said rotatable structure and being eccentricaliy oil'set withvreference to the axis oi rotation ot said structure, and anti-frictionrolling members between said ring and said mounting. said ring onrotation oi said rotatable structure imparting movement to said saidmovable element in each o! the seta successively soas to allow directcurrent to be supplied to said wind#y ings successively.

3. An electric machine comprising a stationary structure, a continuouslyrotatable structure incorporating a permanent magnet armature and ashaft onwhich said armature is mounted, a plurality of polebodiesincorporated in the stationary structure and presenting to said armaturea plurality of`poles at angularly spaced positions with reference to theaxis of rotation oi the rotatable structure, windings awlied to' saidpole bodiestherebeing awindingior each pole body,

a current continuer consisting of sets oi intercontactible elementsresiliently urged to assume non-contacting position, there being a seto! such` elements connected electrically in circuit with thewindingforeachpolebodyandthesets'being mounted at iixed locations on thestationary structure which locations fare angularly spaced by amountscorresponding tothe angular spacing of the poles oi'the respective polebodies, an inner ring tast on an eccentrically odset portion ot saidrotatable structures shaft. an outer ring ireely-rotatabb mounted on.said inner ring, anti-friction rolling members between said outer andinner rings, a movable one oi',said elements in each currentcontrollerset which element said outer ringwherebylonrotationoisaidshai'ttheelementsoithecurrentf continuer sets are causedtoassume inter-contacting Positions once per rcvolution'of said L'Anelectric machine comprising astationary structure including a housmg, acontinuously rotatable structure incorporating a permanent magnet and ashaft'on whichsaid armature is mounted, a plurality ot elongated polebodie'sincorporated4 in said stationary structure disposed at angularlyspaced positions with reference to the axis of rotation of saidrotatable'structure and each with its length parallel to said axis, the.

polebodiesbeinglocatedononeaxiallyfacingsideofsaidarmatureandthepolebodieshaving their one ends adjacent saidarmature side. en

larged pole-forming heads on said ends. an insulating 'mountingsupporting said ends, a lam-l inated iron mounting1 supporting the otherends of said pole bodies. said insulating mounting and saidlaminated-iron mounting each being constitutedasatransversepartitionlngwallinsaid homing, a bearing for the armsture's shaft on said insulatingmounting, a second bearing for said shaft on the housing and at theopposite axially-facing side of the armature from said pole bodies,windings applied around said pole bodies there being a winding for eachpole body with its axis parallel to the length thereof, means forsupplying direct current to said windings, a current controller betweensaid armature and said second bearing, said current-controllerconsisting of sets of inter-contactible elements resiliently urged toasume non-contacting positions.'there being a set of such elementsconnecied electrically in circuit with the winding for each pole bodyand the sets being mounted at ilxed locations on the stationarystructure which locations are angularly spaced by amounts correspondingto the angular spacing oi' the poles of the respective pole bodies, aninner ring mounted fast on an eccentrlcally odset portion of said shaftwhich portion is located between said armature and said second bearing,an outer ring freely-rotatably mounted on said inner ring, anti-frictionrolling members between said outer and inner rings, a movable one ofsaid elements in each current-controller set which element bears againstsaid outer ring. whereby on rotation of said shaft the elements of thecurrentcontroller sets' are caused to assume inter-contacting positionsonce per revolution of said shaft.

6. An electric machine comprising a stationary structure including ahousing. a continuously rotatable structure, at least three elongatedpole bodies incorporated in said stationary structure disposed atangularly spaced positions with reference to the axis of rotation ofsaid rotatable structure and each with itsr length parallel to saidaxis, a disc-like member and shaft therefor incorporated in thecontinuously rotatable structure, the disc like member being locatedwith one axially-facing side adjacent the one end of said pole bodiesand consisting of two complementary sector shaped components whereof oneis constituted by a, Permanent magnet of less than semi-circular areaand whereof the other is constituted by insulating material. anironmounting supporting the other ends of said pole bodies. windingsapplied around said pole bodies, there being a windingfor each pole bodywith its axis parallel to the length thereof, a perma- I nent magnetincorporated in the stationary structure co-axial with said rotatablestructure and with an end adjacent said disc-like member's controllerconsisting of sets of inter-contactible 7s elements resiliently urged toassume non-contacting positions, there being a set of such elementsconnected electrically in circuit with the winding for each pole bodyand the sets being mounted at fixed locations on the stationarystructure which locations are angularly spaced by amounts correspondingto the angular spacing of the poles of the respective pole bodies, aninner ring fast on an eccentrically offset portion of said shaft whichportion is located between said disc-like member and said secondbearing. an outer ring freely-rotatably mounted on said inner ring,anti-friction rolling members between said outer and inner rings, s.movable one of said elements in each current-controller set whichelement bears against said outer ring, whereby on rotation of said shaftthe elements of the current-controller sets are caused to assumeintercontacting positions once per revolution of said shaft.

6. An electric machine comprising a. stationary structure, acontinuousLv rotatable structure incorporating a permanent magnetarmature, a plurality of pole bodies incorporated in the stationarystructure and presenting to said armature a plurality of poles atangularly spaced positions with reference to the axis of rotation of therotatable structure, windings applied to said pole bodies there being awinding for each pole body, means for supplying direct current to saidwindings, a current-controller connected electrically in circuit withsaid windings, the current-controller consisting of outer and innerspaced concentric contact-rings and resilientcontact elements projectingbetween said contact rings, and an eccentric-like member rotatable withsaid rotatable structure and bearing on said resilient contact-elements,said member on iotation of said rotatable structure oscillating thecontact elements from positions of contact with one of said contactrings to positions of contact with the other of said contact ringsthereby actuating said current controller, the current controller beingadapted on actuation to reverse the direction of current in the coilssuccessively and thereby create a rotating magnetic ileld.

'1. An electric machine comprising a stationary structure, acontinuously rotatable structure incorporating a permanent' magnetarmature. a plurality of pole bodies incorporated in the stationaiystructure and presenting to said armature a plurality of poles atangularly spaced positions with reference to the axis of rotation of therotatable structure, windings applied to said pole bodies there being awinding for each pole body, a positive lead and a negative lead forsupplying direct current to said winding, a currentcontroller connectedelectrically in circuit with said windings, the current-controllerconsisting of fixed outer and inner spaced concentric contact-ringsconnected the one to said positive lead and the other to said negativelead and pairs of movable contact-elements to'contact with said ringsthere being a, pair of elements for each winding connected to therespective ends there` of, and means on the rotatable structure actingon the contact elements to-move them from positions of contact with oneof said contact rings to positions of contact with the other saidcontact rings. the said meaf acting=-on rotation of the rotatablevstructure simultaneously on the elements of a pair andsuccessively onthe pairs of elements and constraining the elements of a pair to contactwith dinerent contact rings.

8.1nane1ectricmachinecomprlsingastator,.

electro-magnets on the stator, a rotor incorporat ing an armature forthe magnets. electric connectionsiromtbemagnetstoasourceoiexcitinzcurrent and contacts in said connections, the combination oi aneccentric on said rotor to rotate therewith and a ring freely Jcurnalledon said eccentric and operatively associated withsaidcontactstccloseandopenthemandthus excite the magnets sequentiallyunder the control oi' said eccentric.

9. In an electric machine comprising a stator, ansularly spacedelectro-magnets on the stator, a rotor incorporating an armature for themsgnets, electric connections from the magnets to a source of excitinscurrent and pairs ot contacts mounted on the stator and interposed insaid connections, the combination ci an eccentric on said rotor torotate therewith, a ring surv them andthus excite the magnetsseqntiaiiy,

rounding said eccentric, a roller-bearing between 20 said eccentric andring. and members angularly spacedsimilsrlytothemagnetsandmmmtedonthsstatorsoastcbearuponsaidng.saidmemberseachbeingconnectedtoonecontactoieach -5otsaidpairsoicontactssoastoclossandopen under the control oi saideccentric.

i0. In an electric machine comprising a stator. anzularly spacedelectro-magnets on the stator. and a rotor incorporating a permanentmasnet which constitutes an armature for lthe magnets, the combinationof movable contact elements angular-1y spaced similarly to the macnets,there being one oi said elements for each maenet, stationary contactelements engageable one at a time by the individual movable contactelements, all of said contact elements beins interposed between electricterminals of different polarity andthe respective magnets, an eccentricon said rotor. andarinzfreelyjonrnalledonsaideccentrie and operativelyassociated with said movable contact elements to move them under thecontrol otsaideccentricimmonetotheotherotsaid stationary contactelements in order to sequentially mersise and keep reversing thepolarity of the masnsts.

HHNRICH LIST.

